1. Dear Drugs-Forum readers: We are a small non-profit that runs one of the most read drug information & addiction help websites in the world. We serve over 4 million readers per month, and have costs like all popular websites: servers, hosting, licenses and software. To protect our independence we do not run ads. We take no government funds. We run on donations which average $25. If everyone reading this would donate $5 then this fund raiser would be done in an hour. If Drugs-Forum is useful to you, take one minute to keep it online another year by donating whatever you can today. Donations are currently not sufficient to pay our bills and keep the site up. Your help is most welcome. Thank you.
    PLEASE HELP

Purification and Cloning of a Broad Substrate Specificity Human Liver Carboxylesterase That Catalyze

Purification and Cloning of a Broad Substrate Specificity Human Liver Carboxylesterase That Catalyze

  1. Coconut
    Evgenia V. Pindel, Natalia Y. Kedishvili, Trent L. Abraham, Monica R. Brzezinski, Jing Zhang, Robert A. Dean, and William F. Bosron

    The Journal of Biological Chemistry
    Vol. 272, No. 23, Issue of June 6, pp. 14769–14775, 1997

    A human liver carboxylesterase (hCE-2) that catalyzes the hydrolysis of the benzoyl group of cocaine and the acetyl groups of 4-methylumbelliferyl acetate, heroin, and 6-monoacetylmorphine was purified from human liver. The purified enzyme exhibited a single band on SDS-polyacrylamide gel electrophoresis with a subunit mass of approximately 60 kDa. The native enzyme was monomeric. The isoelectric point of hCE-2 was approximately 4.9. Treatment with endoglycosidase H caused an increase in electrophoretic mobility indicating that the liver carboxylesterase was a glycoprotein of the high
    mannose type. The complete cDNA nucleotide sequence was determined. The authenticity of the cDNA was confirmed by a perfect sequence match of 78 amino acids derived from the hCE-2 purified from human liver. The mature 533-amino acid enzyme encoded by this cDNA shared highest sequence identity with the rabbit liver carboxylesterase form 2 (73%) and the hamster liver carboxylesterase AT51p (67%). Carboxylesterases with high sequence identity to hCE-2 have not been reported in mouse and rat liver. hCE-2 exhibited different drug ester substrate specificity from the human liver carboxylesterase called hCE-1, which hydrolyzes the methyl ester of cocaine. hCE-2 had higher catalytic efficiencies for hydrolysis of 4-methylumbelliferyl acetate, heroin, and 6-monoacetylmorphine and greater inhibition by
    eserine than hCE-1. hCE-2 may play an important role in the degradation of cocaine and heroin in human tissues.